Furnace for annealing, baking, &amp;c.



N0. 635,025. Patented Oct. l7, I899. W. E. SAUNDERS. FUBNAGEFORANNEALING, BAKING, 81.0. (Application filed Sept. 9, 1898.) (No Mqdel.)4 Sheets-Sheet a,

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FURNACE FOB ANNEALING, BAKING, 81.0.

(Application filed Sept. 9, 1898.)

4 Shaets--Sheet 3.

(No Model.)

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Patented Oct. l7, I899. W. ,E. SAUNDERS.

FURNACE FOR ANNEALING, BAKlNG,'&c.

(Application filed Sept. 9, 1898.)

4 Sheets-Shet 4,

(No Model.)

. plane of section being indicated on Fig. 2 by Nttn ATE? ntros.

FURNACE FOR ANNEALING, BAKING, as.

SPECIFICATION forming part of Letters Patent No. 635,025, dated October17, 1899. Application filed September 9, 1898. Serial No. 690,575. (Nomodel.)

To ctZZ whom it rmty concern:

Be it known that I, WILLIAM E. SAUNDERS, a citizen of the United States,residing at Cleveland, in the county of ()u yahoga and State of Ohio,have invented certain new and useful Improvements in Furnaces forAnnealing, Baking, &c. 5 and I do hereby declare the following to be afull, clear, and exact description of the invention, such as will enableothers skilled in the art to which it appertains to make and use thesame.

My invention relates to ovens or furnaces for baking, annealing,burning, drying, &c., in such manufacturing operations. as the annealingof glass, metals, &c., the burning of pottery, bricks, &C., the bakingof articles made from carbon, terra-cotta, &c., the dry ing of clay,roasting ores, and all analogous drying and heating operations.

The general features of the invention involve a rotary or revolvinghearth, preferably of annular form, located in an annular tunneLlikefurnace so constructed that the material can be subjected to acarefully-graduated temperature, which can be varied and controlled atwill and so as to effect a gradual heating and gradual cooling of thematerial, whereby material maybe continuously loaded on and dischargedfrom the constantly-moving hearth without interrupting its operation,and thus the operation may be rendered continuous and a great saving oftime, labor, and expense effected and a better result obtained, which isthe object of my invention.

I am aware that a rotary hearth is not novel parse; but theconstruction, arrangement, and

combination of parts embraced in the furnace hereinafter described andconstituting the.

furnace as a whole I believe to be novel, and it is these features asset forth in the sub- -,joined claims which substantially constitute myinvention.

In the annexed drawings, Figure 1 represents in horizontal section afurnace so constructed as to embrace my invention, the

the broken line a; 00. Fig. 2 is a vertical section of the furnace,taken on the line y y of Fig. 1. Fig. 3 is a plan view of the furnaceand tramways. Fig. 4 is a vertical section through one side of thefurnace on line 2 z of Fig. 1, showing more clearly some of the detailsof construction. Fig. 5 is a similar section taken through the dues (7.i &c., on the line 1; 'v of Fig. 1. Fig.6 is a sectional detail showingthe furnace constructed with firegrates. Fig. 7 is a-sectional detailshowing the water-draining arrangement. Fig. 8 is a detail showing theunder side of the rack, pinions, &c., for driving the hearth. Figs. 9,10, and 11 are detailsshowing modified forms of construction of thehearth B, in-

volving the use of antifriction devices, 850. Fig. 12 is asectional'detail showing the roofplates a for facilitating the coolingof the discharge end of thefurnace. Fig. 13 is a partial verticalsection through the furnace when constructed to be heated by aregenerative furnace, the plane ofsection passing through a pair ofregenerative checkerworkchambers and being indicated on Fig. 14. by thebroken line to w. Fig. 1A: is a horizontal sectional detail on the planeindicated by the broken line a u on Fig. 13, and shows the arrangementof certain of the fines, the dotted segments on Fig. leindicating notthe underlying structure, but the relative position of the water-pitabove. Fig. 15 is a sectional detail illustrating the arrangement of theheatingfurnaces in tiers. Fig. 16 is a detail showing in plan View theconstruction of the hearth as a series of connected trucks. Fig. 1'7 isa detail showing the same style of construction in side elevation.

The construction of the hearths'shown in Figs. 1, 2, 3, 4, 5, t, '7, 8,12, 13, and 15 is exactly alike and is fully lettered in Figs. at and 5,for, which reason and to avoid confusion some parts of the hearth arenot lettered in the other figures.

In the drawings, A represents the furnace, of substantially annularground plan and having a preferably central stack a, with to possessadvantages of convenience, accessibility, &c., which render it the mostdesirable form, although I do not intend to restrict my invention to theform shown.

The arrangement shown is, however, believed 13 represents the rotaryhearth, which is composed of an iron annular table I), which is faced onits upper surface with a fireproof or refractory coating 19', offire-brick or other suitable refractory material, when it is to beexposed to high temperatures, but may be used without the coating 1)when only moderate temperatures are to be employed, such as would notinjuriously affect the table I). The table I) is shown mounted on.wheels c, which travel on a circular track d, rigid y secured on thebottom of the furnace-chainher. In the drawings I have shown the trackplaced at the bottom of a pit e, sunk in the bottom of the furnace belowthe level of the top of table or hearth B and just wide enough at thetop to give clearance for the movement of the hearth, as best seen in.Fig. 4. This construction is adopted to prevent the flame or heatof thefurnace from reaching any part. of the hearth B except its top, which isprotected by a refractory coating, as stated but it is evident that incases in which the refractory coating (9' is not needed the rail 61 andthe entire hearth may be above the floor a of the furnace-chamber, and Ido not limit myself to a construction in which the hearth is located inthe pit, as shown. As an additional safeguard against the injuriouseffects upon the metal-work 0f the hearth of a longcont-inued hightemperature in the furnace,

1 construct the surface of the sides and bottom of the pit e of awaterproof material such, for instance, as hydraulic cementso as to makethe pit water-tight, and I fill the pit with water high enough to makecontact with the under side of the hearth, as seen in Figs. 2, 4, 7, &c.This water-cooling of the metal-work of the hearth effectually preventsthe warping or buckling of the hearth and the injurious effects ofrepeated heating and cooling to which it would otherwise be subjected,andas the refractory coating 1) is very little, if at all, affected andis very easily repaired or replaced if it is injured the hearth ispreserved and maintained indefinitely true and rigid without requiringrepair or substitution of parts aside from the natural effects of wear.The water also acts as a seal to prevent the too free access of air tothe furnace, which might otherwise occur by the air entering the pit eatthe recess B and rising into the furnace-chamber at other points,thereby diluting the hot combustion-gases and reducing their heatingeffect.

The furnace is heated by any usual means and in any preferred manner.Fol-instance, by fuel, gas, or oil burned in burnersff and by thecombustion of fuel on grates g g in furnaces G, (see Figs. 6 and 15,) orwhere very intense heat is required the common and well-knownregenerative furnace may be employed, as shown in Fig. 13, thechecker-work or regenerative chambers G being located at each side ofthe furnace A and communicating at, bottom with a flue 9 from which by aflue 22 beneath the pit e the combustiongases are conducted to the stackin any manner preferred, as by discharging into vertical lines 23,(shown in dotted lines in Fig. 13), which open into the chamber of thefurnace A, from which they pass by flues t', &c. The usualreversal-valve 21 serves to change the course of the combustion-gases atintervals in the usual method of operating regenerative furnaces. Thegrates or oil-burners are located at or a little above the level of thetop of the hearth, and where a very intense heat is required may be intwo tiers, one above the other, as shown in Fig. 15; but as the heatwill naturally be greatest near the top of the furnace two tiers willseldom be required.

At a point near the grates 0r burners the furnace is so recessed on itsouter side as to expose the hearth for a distance sufficient to affordconvenient room for loading on and discharging material therefrom, asshown at B in Fig. 1. From the recess B to or nearly to the grates orburners the furnace-chamber is only enough wider than the hearth toafford clearance for the hearth and its load, as indicated at a in Fig.l, and the narrow space thus left ad mit-sa small amount of air betweenthe load and the furnace-wall, which not only aids the combustion in thefurnace-chamber, but also serves to slowly cool the articles or materialon the hearth. The furnace-walls in the neighbtn'hood of the grates orburners be come in time intensely hot, and for some distance back of thegrates the air which thus enters the part a is being subjected to heatradiated from the furnace-walls, and is thus sufliciently warmed toprevent too-rapid cooling of the material on the hearth, but stillexerts a slow cooling effect, which increases very materially as thedistance from the grates or burners increases, so that by the time theslowly-moving hearth has brought the material around to the recess B ithas been slowly and. gradually cooled to the desired degree and is readyto be removed from the hearth and replaced by fresh material.

For a short part of its length at the entrance end the furnace is alsonarrowed so asjustto give clearance forthe hearth and its load, asindicated at a in Fig. l, and from thence widens more or less graduallyto its full width. The last one of the fines 2' 2' &c., is located nearthe point where the widening of the furnace-chamberfrom the part abegins, and the liames and hot combustion-gases traverse to a greater orless extent all of the furnacecham her from the grates, gas-fines, oroil-.bu rners around to the last one of the lines 13, 850., thus heatingto a high temperature all of the furnace-chamber except the contractedportions a a which are cool at theirouterends nearthe recess B andgrowgradually warmer as they approach the hotter parts of the furnace.From the recess B, where the material enters the furnace, it is beingslowly and gradually heated by radiation from the heated walls of thefurnace, which effect is moderated by'the slight inward current of airfrom the recess B, so that when the material reaches the point where itfirst encounters the hot furnace-gases it has become partly heated, andas it passes on around toward the burners or grates, where the heat ismost intense, is gradually heated up to the required degree, and then,entering the contracted part a, gradually cooled, as described.

From the grates or burners the furnacechamber is widened enough toafford full play for the flames and hot combustiongases upon, over, andamong the material on the hearth or the saggars in which it may beplaced, and this wider space is continued for asufficientdistancesayone-half,two-thirds, three-quarters, or even more ofthe remainingdistance around to the recess B-so as to insure the exposure of thematerial on the hearth to the heat for a sufficient time.

To effect the proper distribution of the heat in a furnace of this classrequires very careful management and in the furnaces ordinarily used isa matter of difficulty and frequently of imperfect attainment. With theobject of securing a perfect distribution and regulation of the heat Iprovide at numerous points flu'es t" t i &c., which communicate with thefurnace-chamber at different levels and connect with the fines 0; a? athe, which extend to the stack. Dampersjj", &c., are provided atsuitable points in the fines t" 4?, the, as shown in Fig. 5, by means ofwhich dampersthe hot gases may be drawn from any desired part of thefurnace-chamber, and by the same means, in connection with dampers It inthe fines a a 650., the gases may be drawn off at any desired part ofthe length of the furnace-chamber and in any proportion at differentpoints or different levels, as preferred. I

By m ans of the above-described system of fines and dampers the flamesand heating gases can be made to traverse any desired portion of thelength of the furnace, even to the fines a and can be directed to eitherside or to the top or bottom of the chamber and distributed in just theproportion required in any part. With a view of aiding the judiciousregulation of the heat .I provide the furnace at suitable points withattachments for pyrometers Z Z, by which the temperature in thedifferent parts of the furnace can be determined, and thus the operator,by means of the dampers, &c., is enabled to regulate the temperature andthe time during which the material is subjected to it in accordance withthe requirements of the particular material under-treatment. Thepyrometers may of course be made permanent fixtures of the furnace, ifpreferred.

With the double purpose of protecting the furnace-walls at the partwhere they are most severely taxed and of increasing the heating effectof the fires I form air-fines m m (shown in Fig. 4.) in that portion ofthe furnace-walls forward'of the grates or burners, which is of coursethe most highly heated portion, and

these flues open into the fire-pit of the grates or into the air-chamberin which the oilburner is set, so as to supply the highly-- heated airfrom the fines 'm m to the oombus quickly absorb the heat from thematerial on the hearth, and for the same purpose the top of thefurnace-chamber in a may be made of iron 'plates a", (see Fig. 12,)whose greater heat conductivity will cause them to absorb and radiateheat more rapidly than would the brickwork of the walls.

The hearth Bis rotated continuously or intermittently at the proper ordesired speed by any suitable means-esuch, for instance, as a pinion pmeshing with a rack 0 on the periphery of table b, and preferably on itsun der side, the pinion being actuated, as by gear 19 on the shaft g, byany suitable power. While I have shown the hearth-mounted on wheelswhose axle-boxes 0 Fig. 4, are at tached to the framework 19 whichcarries the table I), and I prefer this arrangement, it is within myinvention to support the hearth on fixed rollers 0, balls r or wheels soarranged as to permit its rotation without lateral movement and todispense with the track trucks 24 instead of a solid hearth, as seen inFigs. 16 and 17.

In the drawings I have shown the furnace of a height sufficient to allowof the piling of saggars 3 upon the hearth, as would be done in burningpottery and other articles, and a similar height might be used inburning brick,

.tion products travel in their passage from the grates, fines, orburners to the fines 71 '6 &c., on their way to the stack. As shown inthe drawings, the hearth, as shown by the arif the nature of thematerial treated or other circumstances shouldrender it preferable.

The pit is so constructed as to drain to one point, at which point anarm e of the pit extends beyond the furnace-Wall and is provided with anoutlet to a sewer or other convenient discharge. I A stand-pipe cconnecting with the sewer, maintains the water in the pit e at aconstant level and serves as an overflow-pipe in case a circulation ofwater through the pit is maintained, as may be desirable. Bya suitablevalve 6 openinginto pipe 6 at the bottom or other means, the pit can bedrained of its water and workmen can then enter the pit beneath thehearth for the purposes of inspection or repair. Preferably I locate theshaft 6 in this arm or extension 6 of the pit e, and the shaft andpinion are thus brought below the water-level, as seen in Fig. 7, inwhich the outlet to a sewer is shown in dotted lines beneath pipe 6 Forspeed and convenience in handling I provide one or more elevated tracksH leading from the recess B to such points as the material may be takenfrom or to. By means of trolleys on these tracks carrying suspend edslings, hooks, or platforms T the untreated material is broughtto thefurnace and the finished articles or materials conveyed to any desiredpoint. By means of the common switch 75 used in such tracks the trolleysbring the raw material on track 6 and return on track t, loaded withfinished material.

In the claims I have used the term burners in the broad sense ofcombustion apparatus of any kind, meaning to include in that termfire-grates, gas-burning fines, oil-burners, gas-burners, or any meansof supplying heat to the furnace-chamber by combustion.

What I claim as my invention, and desire to secure by Letters Patent,is-

1. A furnace having an annular heatingchamber and a conti-nuously-movingwater- .cooled hearth therein, substantially as described.

2. A furnace having an annular heatingchamber, an annular water-pit inthe bottom of said chamber, an annular hearth in said pit and in contactwith the water, and means for rotating said hearth, substantially asdescribed.

3. A furnace having an annular heatingchamber contracted in the portionadjacent to the point of discharge, an annular hearth traversing in saidchamber, a stack, and a plurality of fines connecting the stack withdifferent parts of said heating-chamber, substantially as described.

4. A furnace having an annular heatingchamber recessed at the point ofdischarge and contracted in the portions adjoining said recessed part,an annular hearth traversing in said chamber and through said recess, astack, and a plurality of fines connecting the stack with differentparts of the heatingchamber, substantially as described.

5. A furnace having an annular heatingchamber contracted in the portionadjacent to the point of discharge, an annular hearth having arefractorycoating and traversing in and a plurality of fines connectingdifferent parts of the heating-chamber with the stack, substantially asdescribed.

7. A furnace having an annular heatingchamber recessed at the point ofdischarge, a continuously-moving annular hearth traversing in saidchamber and through said recess, a stack, and a plurality of fiuesconnecting different parts of the heating-chamber with the stack,substantially as described.

8. A furnace having an annular heatingchamber-contracted in the portionadjacent to the point of discharge, a water-pit in. the bottom of saidchamber, an annular hearth traversing in said chamber and in contactwith the water in said pit, a stack, and a plurality of fines connectingthe stack with different parts of the furnace-chamber, substantially asdescribed.

9. A furnace having an annular heatingch-amber recessed at the point ofdischarge and contracted in the portion adjacent to the recessed part, awater-pit in the bottom of said chamber, an annular hearth traversing insaid chamber and vin contact with the water in said pit, a stack, and aplurality of fines connecting the stack with different parts of thefurnace-chamber, substantially as de scribed.

10. A furnace having an annular heatingchamber with a water-pit therein,an annular hearth traversing in said chamber and in contact with-theWater in the pit, a central stack, and a plurality of fines connectingthe stack with different parts of the heating-chamber, substantially asdescribed.

11. A furnace having an annular heatingchamber contracted in the portionadjacent to thepoint of discharge, an annular heart-h traversing in saidchamber and with its load substantially filling said contracted portion,fire chambers or burners communicating with the wider part of thechamber, a stack, and a plurality of fines connecting the stack withdifferent parts of said heating-chamber, substantially as described.

12. A furnace having an annular heatingchamber contracted in the portionadjacent to the point of discharge, an annular hearth traversing in saidchamber and With its load substantially filling the contracted portion,burners or combustion-chambers communicating with the wider part of thefurnacechamber, a stack, a plurality of fines connecting the stack withdifierent parts of the heating-chamber, and air-fines located in thewalls of the contracted portion and communicating with the outer air forcooling the,

discharge end of the furnace, substantially as described.

13. A furnace having an annular heatingchamber contracted in the portionadjacent to the point of discharge and formed in part and air-fines inthe walls of.the contracted portion communicating with the outer air,whereby the cooling of the contents of said contracted portion of thefurnace is accelerated, substantially as described.

14. A furnace having an annular heatingchamber recessed at the point ofdischarge and contracted in the portion adjacent to said recess, saidcontracted portion being formed in part of metal, an annular hearthtraversing in said chamber and With its load substantially filling saidcontracted porti0n,bnrners communicating with the Wider part of thechamber, a stack, fines connecting said stack with the furnace-chamber,and air-fines in the Walls of the contracted portion communicating withthe outer air, whereby the cooling of the contents of said contractedportion of the furnace is accelerated, substantially as described.

15. In a furnace the combination of an annular heating-chamber having aWater-pit therein, an annular hearth traversing in said chamber and incontact with the Water in said pit, a central stack, a plurality offines conmeeting said stack with different parts of said chamber,burners in the Walls of said chamber, air-heating fines in thefurnace-Walls opening to the outer air and connecting with said burners,and cold-air flnesin the fur mace-Wall between the burners and the pointof discharge, substantially as described.

16. In a furnace the combination of an annular heating-chamber recessedat the point of discharge and having a water-pit in its bottom, anannular hearth traversingin said chamber and through said recess incontact with the Water in said pit, a central stack, a plurality offines connecting said stack with different parts of said chamber,burners in the Walls of said chambers, air-heating fines in thefurnace-Walls opening to the onter'air and connecting'witli said.burners, cold-air fines in the furnace-walls adjacent to the point ofdischarge, and tracks entering said recess for loading and dischargingthe hearth, substantially as described.

17. In a furnace the combination of an annular heating-chamber recessedat the point of discharge and contracted atthe portions adjacent to saidrecess, a water-pit in the bottom of said furnace-chamber and recess, atrack in the bottom of said pit, an annular hearth'snpported on saidtrack and traversing in said chamber and through said recess in contactwith the water in said pit, acentral stack, a plurality of fluesconnecting said stack with different parts of said chamber, burners inthe walls of said chambers, airheating fines in the furnace-wallsopening to the outer air and connecting with said burners, cold-airfines in the furnace-Walls adjacent to the point of discharge, andtracks entering said recess for loading and discharging the hearth,substantially as described.

In testimony whereof I hereto affix my sig= nature in presence of twowitnesses.

WILLIAM E. SAUNDERS.

Witnesses:

,OEOIL L. SAUNDERS,

J. B. BAnRoW.

